How to check if character in string is a letter? Python

问题

So I know about islower and isupper, but i can't seem to find out if you can check whether or not that character is a letter?

Example:

s = 'abcdefg'
s2 = '123abcd'
s3 = 'abcDEFG'

s[0].islower() = True
s2[0].islower()= False
s3[0].islower()=True

is there any way to just ask if it is a character besides doing .islower() or .isupper() ?

回答1:

You can use isalpha(), see the docs at http://docs.python.org/2/library/stdtypes.html

An example:

>>> s = "a123b"
>>> for char in s:
...     print char, char.isalpha()
... 
a True
1 False
2 False
3 False
b True

回答2:

str.isalpha()

Return true if all characters in the string are alphabetic and there is at least one character, false otherwise. Alphabetic characters are those characters defined in the Unicode character database as “Letter”, i.e., those with general category property being one of “Lm”, “Lt”, “Lu”, “Ll”, or “Lo”. Note that this is different from the “Alphabetic” property defined in the Unicode Standard.

In python2.x:

>>> s = u'a1中文'
>>> for char in s: print char, char.isalpha()
...
a True
1 False
中 True
文 True
>>> s = 'a1中文'
>>> for char in s: print char, char.isalpha()
...
a True
1 False
� False
� False
� False
� False
� False
� False
>>>

In python3.x:

>>> s = 'a1中文'
>>> for char in s: print(char, char.isalpha())
...
a True
1 False
中 True
文 True
>>>

This code work:

>>> def is_alpha(word):
...     try:
...         return word.encode('ascii').isalpha()
...     except:
...         return False
...
>>> is_alpha('中国')
False
>>> is_alpha(u'中国')
False
>>>

>>> a = 'ａ'
>>> b = 'a'
>>> ord(a), ord(b)
(65345, 97)
>>> a.isalpha(), b.isalpha()
(True, True)
>>> is_alpha(a), is_alpha(b)
(False, True)
>>>

回答3:

I found a good way to do this with using a function and basic code. This is a code that accepts a string and counts the number of capital letters, lowercase letters and also 'other'. Other is classed as a space, punctuation mark or even Japanese and Chinese characters.

def check(count):

    lowercase = 0
    uppercase = 0
    other = 0

    low = 'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'
    upper = 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'



    for n in count:
        if n in low:
            lowercase += 1
        elif n in upper:
            uppercase += 1
        else:
            other += 1

    print("There are " + str(lowercase) + " lowercase letters.")
    print("There are " + str(uppercase) + " uppercase letters.")
    print("There are " + str(other) + " other elements to this sentence.")

回答4:

data = "abcdefg hi j 12345"

digits_count=0
letters_count=0
others_count=0

for i in userinput:

    if i.isdigit():
        digits_count +=1 
    elif i.isalpha():
        letters_count +=1
    else:
        others_count +=1

print("Result:")        
print("Letters=", letters_count)
print("Digits=", digits_count)

Output::

Plesae Enter Lerrers with Numbers:
abcdefg hi j 12345
Result:
Letters= 10
Digits= 5

By using str.isalpha() yoy can check if it is letter.

回答5:

this code works:

str=raw_input("enter a string:")
    for char in word:
        if not char.isalpha():
            sum=sum+1
        if sum>0:
            print char

来源：https://stackoverflow.com/questions/15558392/how-to-check-if-character-in-string-is-a-letter-python

标签

python

string

find